Influence of Softening Effect of Bubble Water on Cavity Resonance

This paper studies the nonlinear resonance of a cavity in an aqueous medium containing bubbles, and the resonance frequency is produced by mixing of nonlinear frequencies. We use the model to simulate the nonlinear interaction between ultrasound and bubble dynamics, which is derived from the wave equation and the Rayleigh-Plesset equation based on finite volume and finite difference. The simulation results reveal the existence of cavity resonance frequency shift at the difference frequency component. The frequency shift increases with the increase of the pressure amplitude. It can be considered that this is caused by the softening effect of the medium. Finally, this article shows that nonlinear resonance frequency shift can be used to enhance the amplitude of the difference frequency component, which provides a new idea for subsequent target detection and recognition.